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Lightwave Technology, Journal of

Issue 1 • Date Jan. 1997

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Displaying Results 1 - 18 of 18
  • Correction to "Fabrication of a Pencil-Shaped Fiber Probe for Near-Field Optics by Selective Chemical Etching"

    Publication Year: 1997 , Page(s): 162
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (12 KB)  

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  • Prediction of close-to-zero modal dispersion over a wide range of wavelengths in singly clad multimode fibers

    Publication Year: 1997 , Page(s): 121 - 124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    A numerical analysis of second- and third-order modal dispersions in singly clad multimode optical fibers is presented. We show that, because of their cutoff properties, singly clad multimode optical fibers could provide modal dispersions characteristics similar to those observed in multiclad single mode fibers View full abstract»

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  • Dispersion equalization of a 10 Gb/s repeatered transmission system using dispersion compensating fibers

    Publication Year: 1997 , Page(s): 31 - 42
    Cited by:  Papers (26)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    We have investigated theoretically and experimentally the transmission performance of a 10 Gb/s repeatered transmission system using dispersion compensating fibers (DCFs), The system configuration that we considered is a 360 km standard (1300 nm zero-dispersion) fiber transmission system with an optical repeater including DCF's located every 120 km (or every 2100 ps/nm dispersion). The transmitter was a DFB-laser externally modulated by a zero-chirp LiNbO3 modulator with NRZ (non-return to zero), 223-1 PRBS data. The system performance is evaluated in terms of electrical eye margin in the receiver/regenerator. We present a complete description of the system performance including the nonlinear SPM (self-phase modulation) effect in both standard fibers and DCFs. The results of this investigation clearly demonstrate that the use of DCF's is an extremely effective method to overcome the chromatic dispersion in high-speed transmission systems. The main results of this study are (1) the new “eye position method” which presents the eye margin degradation from both “1” and “0” levels as a function of dispersion values describes the system performance more effectively than the conventional “EOP (eye opening penalty) method”, (2) a rule of thumb is that the total dispersion must be slightly undercompensated to include the SPM effect, (3) a very wide range of dispersion compensation values offers acceptable system performance, and (4) the “equal modular compensation” which is desirable from a practical point of view provides sufficiently large eye margin (33.3% for 10-15 BER after 360 km) although the “customized modular compensation” where the dispersion compensation is tailored to achieve the maximum eye margin without considering the performance at the intermediate repeater locations provides the largest eye margin (48.5% for 10-15 BER) View full abstract»

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  • General noise analysis of recirculating delay line structures

    Publication Year: 1997 , Page(s): 102 - 111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Recirculating delay lines have value notably as sensors and optical signal processors. One of their main limitations is that phase noise from the source is converted to amplitude noise at the detector and that intensity noise is also filtered by the system. An expression is derived for the filtering effect that a recirculating delay line topology has on both the source noise and amplified spontaneous emission from in-line amplifiers. From these expressions it is shown that some delay line topologies have far superior noise characteristics compared to others View full abstract»

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  • Forward error correcting codes in synchronous fiber optic transmission systems

    Publication Year: 1997 , Page(s): 43 - 52
    Cited by:  Papers (12)  |  Patents (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    This paper proposes forward error correcting (FEC) code for synchronous digital hierarchy (SDH) fiber optical transmission systems. They are (18880, 18865) and (2370, 2358) shortened Hamming codes and are encoded at the multiplex-section layer; the check bits are embedded in auxiliary multiplex-section overhead (MSOH) bytes. The codes realize general circuit configurations regardless of the transmission speed or path-size, perfect compatibility with SDH format, suppressed processing delay accumulation, and decrease the chance of line-switching in the case of signal degradation. To ensure that the various requirements of each network-provider such as customized usage of SOH bytes and affordable circuit scale could be satisfied, a trial circuit board was constructed on the programmable hardware called PROTEUS, which enables flexible operation in terms of code-selection and check bit area. We actually confirm error-correcting capability through the first STM-64 FEC-coded-optical transmission experiment. The statistics of error occurrence in the optical transmission line are also studied. The result indicates that the proposed codes are effective in optical transmission systems if the BER is limited by optical noise and dispersion View full abstract»

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  • Reduction of excess intensity noise in spectrum-sliced incoherent light for WDM applications

    Publication Year: 1997 , Page(s): 53 - 61
    Cited by:  Papers (27)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (216 KB)  

    We investigate wideband reduction of excess intensity noise in incoherent light for application to spectrum-sliced WDM systems. The noise reduction scheme is based on optoelectronic feedforward compensation. We derive expressions for the probability density function of noise-reduced incoherent light and present measurements that are in good agreement with theory. We evaluate the significant levels of improvement obtainable in the capacity of spectrum-sliced WDM channels. For example, to obtain a signal-to-noise ratio of 50, a noise-reduced channel requires six times less optical bandwidth than a spectral slice without noise reduction View full abstract»

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  • Theoretical and experimental analysis of clipping-induced impulsive noise in AM-VSB subcarrier multiplexed lightwave systems

    Publication Year: 1997 , Page(s): 20 - 30
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    A new theoretical and experimental analysis of clipping-induced impulsive noise in directly modulated AM-VSB/digital hybrid lightwave systems is presented. The theoretical model is based on asymptotic clipping and shot noise theories, and the probability density of combined Gaussian and impulsive noise is obtained by performing a numerical inverse Fourier transform on the closed-form characteristic function. Similar analyzes in previously published work have resulted in closed-form expressions for the BER in hybrid AM-VSB/QAM systems, but these models, which do not use the numerical inverse Fourier transform, have either required the use of an experimentally measured clipping rate using a spectrum analyzer or have had limited BER prediction accuracy. Application of our theory to experimental results for the BER in a hybrid AM-VSB/64 QAM system demonstrates that the performance of the model if better than the models of previously published works. Theoretical analysis of a similar hybrid system employing the N-VSB HDTV digital modulation format rather than QAM indicates that an improvement in BER is achieved if 8-VSB at double the symbol rate is used instead of 64 QAM. We also present the first experimental characterization of the amplitude and time distribution of (1) low-frequency bandpass and (2) down-converted impulsive noise and we show that the time interval between clipping events has a high probability of being 167 μs, 1.5 μs, or 4 ms in an NTSC system with unmodulated carriers. These results have potential impact on forward error correcting codes used to ameliorate the degrading effects of clipping View full abstract»

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  • An efficient wavelength reusing/migrating/sharing protocol for dual bus lightwave networks

    Publication Year: 1997 , Page(s): 62 - 75
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    High-speed lightwave networks employing linear fiber bus topology have become attractive with the emergency of erbium-doped optical amplifiers. Moreover, the huge network capacity in a dual bus lightwave network is obtained by several parallely transmitting channels (wavelengths) on each bus. By applying the wavelength reusing concept, nonoverlapping traffic in the network can be serviced simultaneously to achieve high network throughput. It is also possible that a new incoming request is blocked even the bandwidth between the source and the destination is available. Nevertheless, this request may be accommodated by migrating some existing connections. Due to the number of wavelengths is limited, some requests may further share the same wavelength to improve the network throughput. In this paper, an efficient distributed wavelength reusing/migrating/sharing protocol (WRMSP) for the dual bus lightwave networks (DBLN) is proposed. This protocol consists of three efficient schemes for carrying out the wavelength reusing, migration and sharing, respectively. Simulation results show that for a limited number of wavelengths and tunable receivers, the proposed protocol substantially improve the network throughput and access delay under general traffic demands View full abstract»

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  • Fiber Bragg grating coherence spectrum modeling, simulation, and characteristics

    Publication Year: 1997 , Page(s): 154 - 161
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    The fiber Bragg grating (FBG) coherence spectrum, which comes from mode coupling with both core-bounded and cladding-bounded modes, was modeled and simulated using a dynamic mode selecting rule together with the coupling equations. Grating saturation effects were included in the index distribution modeling for its significant influence on the coupling process. The grating spectrum under normal experimental testing conditions was modeled and simulated for the purpose of experimental analysis and device design View full abstract»

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  • Effects of concentration on the performance of erbium-doped fiber amplifiers

    Publication Year: 1997 , Page(s): 112 - 120
    Cited by:  Papers (55)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    The dependence of erbium-doped fiber amplifier (EDFA) performance on the erbium ion concentration is studied experimentally and theoretically. The quantum efficiency of the amplifier is found to he strongly dependent on the erbium ion concentration, the signal wavelength, and the relative propagation direction of the pump and signal beams. This dependence is fully explained by the presence of an upconversion mechanism between ions residing in pairs or larger clusters and suggests that other sources of amplifier performance degradation (back-ground loss, excited state absorption, homogenous upconversion) are negligible. The experimental data show that in the present EDFA designs with over 80% quantum/conversion efficiency, the aluminum co-doped fibers with erbium ion concentration less than 20×1024 m-3 (900 molar ppm Er3+) are most suitable View full abstract»

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  • 2×2 buffered switch fabrics for traffic routing, merging, and shaping in photonic cell networks

    Publication Year: 1997 , Page(s): 86 - 101
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    An approach to optical packet switching is discussed, which uses small, simplified optical elements for traffic routing, merging, and shaping. The elements are constructed from 2×2 switches and optical delay lines, and may be implemented in a variety of technologies. They are designed for use with deflection routing, and even when using only six switches in a module, a deflection probability of 2.8×10-7 is possible with a load of 0.8. The modules may also be used as 2×1 mergers where a deflection probability of 10-12 is possible with six switches and a total load of 0.8. The BER performance of the modules is simulated with respect to crosstalk, with even relatively poor switch devices of -18.5 dB isolation yielding a power penalty of less than 1 dB. A networking strategy radically different from today's is discussed, driven by the need to reduce hardware, software and operating costs View full abstract»

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  • Performance analysis preclipping AM/QAM hybrid lightwave systems

    Publication Year: 1997 , Page(s): 1 - 5
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    A model is presented for the analysis of the clipping noise in preclipping AM/QAM hybrid lightwave systems. It is shown that the clipping-induced degradation of BER performance can be reduced by preclipping the signal. It is also shown that the recurrence of the signal tips after passing through the low-pass filter presents a serious limit to the performance improvement achievable by the preclipping technique View full abstract»

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  • Fabrication of light-turning mirrors in buried-channel silica waveguides for monolithic and hybrid integration

    Publication Year: 1997 , Page(s): 148 - 153
    Cited by:  Papers (8)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    A technique for incorporating a mirror into the core of a silica-based channel waveguide is described. Both up reflecting mirrors for hybrid integration and down-reflecting mirrors for monolithic integration can be fabricated using this technique. The proposed fabrication method is based on a combination of low temperature hollow cathode PECVD for silica-based waveguide deposition and a novel technique for forming a reflecting facet by wet chemical etching of PECVD silica View full abstract»

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  • Wavelength stabilization in packet-switched WDM networks

    Publication Year: 1997 , Page(s): 76 - 85
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    We demonstrate a novel wavelength stabilization technique for use within packet-switched wavelength division multiplexed (WDM) networks. The technique stabilizes transmitters against long-term wavelength drift, as short-term and switching-induced wavelength drifts are considered manageable in WDM networks using channel guard bands. The accuracy, capture range, and performance of the wavelength stabilization scheme is investigated. Long-term wavelength stabilization of a DBR laser is demonstrated which is suitable for networks with channels spacings of 30 GHz or less View full abstract»

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  • Rotation of the polarization plane in optical fibers

    Publication Year: 1997 , Page(s): 144 - 147
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    The rotation of the polarization plane of a light wave traveling in an optical fiber that lies on a space curve based on parallel transport is described. An estimation of the effect due to winding the fiber is presented View full abstract»

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  • Nondestructive position-resolved measurement of the zero-dispersion wavelength in an optical fiber

    Publication Year: 1997 , Page(s): 135 - 143
    Cited by:  Papers (16)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    We describe a new technique for mapping the distribution of the zero-dispersion wavelength in a span of optical fiber. With this technique, which is based on four-wave mixing of short pulses, we obtained a spectral accuracy of ±0.2 nm and a spatial resolution of 700 m. Theoretical analysis agrees well with experimental results and points to an order of magnitude improvement in spatial resolution using shorter pulses. Spatial resolutions less than 100 m may be necessary because we find, by destructive measurements, variations in lambda-zero by as much as 0.5 nm over spans of 500 m View full abstract»

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  • A multilevel soliton communication system

    Publication Year: 1997 , Page(s): 6 - 19
    Cited by:  Papers (5)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    A multilevel soliton communication system is proposed and assessed. In this system, at the transmitter end each channel transmits its data via fundamental solitons with a pre-specified amplitude (i.e., soliton width). At the receiver end we take advantage of the sensitive relationship between the amount or fundamental soliton self-wavelength shift and the width of the soliton in the subpicosecond region. We first compress the incoming soliton noises to the subpicosecond level and pass them through a short length of fiber at the end of which the pulses have become separated in the wavelength domain since each soliton, corresponding to a data channel, has experienced a different Raman self-wavelength shift. The channels are then easily separated by optical filters. We have derived the design constraint relations for such a system. We have then heuristically designed a 40 Gbs (four channels) system for a 1000 km propagation distance (total data-rate distance product of 40 Tb/km). Numerical simulations and noise analyses have verified the feasibility and practicality of the proposed system with very good design margins. The wavelength jitter is found to be much smaller than the desired filter spacing, and thus its contribution to the bit error rate is negligible. We also argue that the system is more tolerant to Gordon-Haus timing jitter than conventional TDM soliton systems. The system is all fiber and is, therefore very cost effective as it does not require sophisticated electro-optic and microwave circuits for demultiplexing. The system can potentially operate at much higher speeds than those achievable in conventional soliton systems and it can be used in parallel with WDM soliton system View full abstract»

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  • Automated fusion-splicing of polarization maintaining fibers

    Publication Year: 1997 , Page(s): 125 - 134
    Cited by:  Papers (6)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    An advanced splicing technique for polarization maintaining (PM) fibers has been derived based on the polarization observation by lens-effect-tracing (POL) method. With this technique, azimuthal alignment on common types of PM fibers can be automatically performed in a passive way by an automated fusion splicer. Because the method permits an accurate estimation of the splice's extinction ratio before and after actual splicing, the quality of the splice call be estimated without having to make an active measurement. The experiment results illustrated in the paper show a mean extinction ratio 32.2 with 2.73 dB standard deviation and mean difference between measured and estimated extinction ratio 0.18 dB, respectively, for six different types of PM fibers View full abstract»

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Aims & Scope

The Journal of Lightwave Technology contains articles on current research, applications and methods used in lightwave technology and fiber optics.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Peter J. Winzer
Alcatel-Lucent Bell Labs